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SSS 2010-09-15

时间:2010-10-08 05:44来源:互联网 提供网友:xn0006   字体: [ ]
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    (单词翻译:双击或拖选)

This is Scientific American’s 60-Second Science, I’m Cynthia Graber. This will just take a minute.

Glaciers1 slowly grind their way over mountains and plains, moving immense boulders2 and carving3 out fjords. That’s true in temperate4 regions, where glaciers – glacially – flow downhill. Over thousands of years, the frozen masses can scrape miles off of mountains. Researchers call it the glacial buzz-saw.

But for the very coldest climes, researchers now offer a counter-intuitive view of glaciers – they actually help mountains grow. The finding was published in the journal Nature.

A team led by scientists from the University of Arizona studied mountains in remote areas of Patagonia in South America. The Andes are actively5 growing. Hot rocks are shoved to the top, and erosion brings them back down the sides. The team collected 146 samples of rocks from mountainsides and then dated the rocks’ so-called cooling age, which reveals when the rock was exposed by erosion.

They found that erosion happened faster in the warmer mountains to the north, and more slowly in the colder mountains in the south. Turns out that when glaciers are cold enough they don’t move much. Instead, they seal the mountains, protecting them from erosion. The scientists call the effect ‘glacial-armoring’: an invaluable6 assist for peak performance

Thanks for the minute, for Scientific American’s 60-Second Science. I’m Cynthia Graber.
 


点击收听单词发音收听单词发音  

1 glaciers e815ddf266946d55974cdc5579cbd89b     
冰河,冰川( glacier的名词复数 )
参考例句:
  • Glaciers gouged out valleys from the hills. 冰川把丘陵地带冲出一条条山谷。
  • It has ice and snow glaciers, rainforests and beautiful mountains. 既有冰川,又有雨林和秀丽的山峰。 来自英语晨读30分(高一)
2 boulders 317f40e6f6d3dc0457562ca415269465     
n.卵石( boulder的名词复数 );巨砾;(受水或天气侵蚀而成的)巨石;漂砾
参考例句:
  • Seals basked on boulders in a flat calm. 海面风平浪静,海豹在巨石上晒太阳。 来自《简明英汉词典》
  • The river takes a headlong plunge into a maelstrom of rocks and boulders. 河水急流而下,入一个漂砾的漩涡中。 来自《简明英汉词典》
3 carving 5wezxw     
n.雕刻品,雕花
参考例句:
  • All the furniture in the room had much carving.房间里所有的家具上都有许多雕刻。
  • He acquired the craft of wood carving in his native town.他在老家学会了木雕手艺。
4 temperate tIhzd     
adj.温和的,温带的,自我克制的,不过分的
参考例句:
  • Asia extends across the frigid,temperate and tropical zones.亚洲地跨寒、温、热三带。
  • Great Britain has a temperate climate.英国气候温和。
5 actively lzezni     
adv.积极地,勤奋地
参考例句:
  • During this period all the students were actively participating.在这节课中所有的学生都积极参加。
  • We are actively intervening to settle a quarrel.我们正在积极调解争执。
6 invaluable s4qxe     
adj.无价的,非常宝贵的,极为贵重的
参考例句:
  • A computer would have been invaluable for this job.一台计算机对这个工作的作用会是无法估计的。
  • This information was invaluable to him.这个消息对他来说是非常宝贵的。
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